Optimized for powering with tealights/candles.
With inspiration from my previous projects:
This was made as an experiment to test efficiency when using water as cooling component in a thermoelectric system. The result was very interesting and as it was really easy to make I thought I could share this too.
It converts heat energy (from candles) into electricity. Main usage is to power LED lights to act as an emergency product. It could also be scaled up and used in homes where electricity is not very given. It could also be used as a battery charger or power other electronic devices. I´m well aware of the commercial product tPOD1 which I think is a great idea but I´m more interesting in a DIY solution for everyone.
I´m using a thermoelectic module, also called peltier element, TEC or TEG. You have one hot side and one cold. The temperature difference in the module will start producing electricity. The physical concept when you use it as a generator it's called the Seebeck effect. Thermoelectic modules are mainly used for the opposite effect, the Peltier effect. Then you apply a electric load and it will force a heat transfer from one side to the other. Often used in smaller refrigerators and coolers. Read more about i here:
First I used a cheap TEC-module (8€) but it was unfortunately destroyed due to high temperatures. It was specified to handle 200ºC max temperature but somehow I got higher temp than I measured. I ran it without load, that might be the cause. I now use a 40x40mm TEG-module that produce 5.9W (4.2V/1.4A) at 180ºC difference. It has a maximum operating temp of 350ºC (180ºC cold side). It was the same module I used in my other charging project. It´s quite expensive though, about 50€. TEGs are a bit hard to come by but I think there are cheaper ones available.
To transport away all heat and cool it with air you usually need a large heat sink, or a small heat sink with a motor and fan. In this project I use water instead. That make the contruction really compact and the temperature on the "cold" side will never exceed 100ºC. Water will eventually boil but it´s easy to refill, as long as you have water.
To power LEDs you need higher voltage than the module itself produce. In my previous project I built an adjustable regulated voltage Step-up. That could be used (and is better) but I choose to use a $1 step-up from Ebay.
The best choice of heat source is 3x tealights. That produce about 0.2W electric power.
- 90g (without LED)
- Built in voltage step-up
- Support for 3x tealights
Mainy constructed to power LEDs but can be used for other things as well:
- Battery/smartphone charger
- External fan (cooling effect, fire booster, etc.)
- Charge super capacitor and power high intensity SOS signals
- Spirit burner/stove
- Gas burner/stove
- Wood stove
- Camp fire
- Hot water